No, DNS is not decentralized. There is a trust issue with decentralizing DNS. The way it works right now, you send your DNS query to a trusted nameserver like Google (8.8.8.8) or Cloudflare (1.1.1.1), and trust that the nameserver returns a correct DNS record. To decentralize this, you would need a way to verify that the DNS records are valid, and not directing you to a malicious phishing site or something like that.
Discussion
Ahhh, okay. That does make it more tricky.
Would could say that “DNS isn’t decentralized per se, but it is partially distributed—hierarchically with a central master registry through which all information must ultimately pass.” Is the central master ICANN?
Yes ICANN is the top level authority for DNS.
https://www.icann.org/en/system/files/files/what-icann-does-22jun12-en.pdf